Is it possible to use k-nearest neighbour for classification with more than two attributes?
The number of features is not important to use K-NN algotihm. You have to decide distance measure to detect neighbors. I share with you some links that you can check to see which kinds of distance measures that you can use. Just decide the meause and use your feature vectors in the measure.
https://www.kdnuggets.com/2020/11/most-popular-distance-metrics-knn.html
https://medium.com/@luigi.fiori.lf0303/distance-metrics-and-k-nearest-neighbor-knn-1b840969c0f4